The Women’s Health Initiative (WHI) is a major, long-term research program designed to address cardiovascular disease, cancer and osteoporosis – the most frequent causes of death, disability and poor quality of life in postmenopausal women. The Hutchinson Center is home to the study's coordinating hub, led by Dr. Garnet Anderson, along with Drs. Ross Prentice, Andrea LaCroix, and Charles Kooperberg.
Launched in 1991 with a $625 million grant from the National Institutes of Health, the WHI is one of the largest U.S. prevention studies of its kind. It initially consisted of clinical trials and an observational study that together involved more than 161,000 postmenopausal women.
The clinical trials tested the effects of postmenopausal hormone therapy, dietary changes, and calcium and vitamin D supplements on heart disease, fractures, and breast and colorectal cancer. Those studies ended between 2002 and 2005.
Since then, more than 115,000 WHI participants have continued providing health information that is being used to investigate a variety of key women’s health questions.
Landmark hormone therapy findings
In 2002, millions of American women woke up to news that would have a profound effect on decisions about their health. The WHI had released findings that combination hormone replacement therapy—at the time prescribed to 15 million postmenopausal women in the U.S. to alleviate symptoms of menopause and to prevent fractures and heart attacks—significantly increased the risk of heart disease, stroke and breast cancer.
Those research findings singularly changed the face of women's medicine around the world. Researchers estimate that because of the decrease in hormone therapy use following the WHI publication, there have been 15,000-20,000 fewer cases of breast cancer each year in the United States.
Since then, women's use of hormone therapy has plunged in the U.S. and many other countries, and this has been followed by measurable decreases in breast cancer in several countries and, in the U.S., decreases in heart attack and stroke.
Fueling breakthroughs in cancers affecting women
Hutchinson Center researchers have made a number of other key findings using WHI data, including:
- Dr. Ross Prentice and colleagues found that a low-fat diet may reduce the risk of ovarian cancer, as well as breast cancer.
- Dr. Anne McTiernan and colleagues found that postmenopausal women who exercise regularly and keep their weight within a normal range had the lowest levels of circulating estrogens – suggesting they may be at lower risk for breast cancer.
- In analyzing a trial of estrogen-only therapy in women who had a hysterectomy, Dr. Garnet Anderson and colleagues found that women who take estrogen by itself are less likely to develop breast cancer.
- Dr. Andrea LaCroix and colleagues found that taking calcium and vitamin D supplements increases bone mineral density and may reduce the risk of hip fractures and death.
- In analyses of genetic data for WHI participants, Dr. Charles Kooperberg and colleagues identified two new areas of the genome that were associated with body height in African American women.
With an award of $55.4 million to the Hutchinson Center in 2011 from the National Heart, Lung and Blood Institute for continued coordination of the study through 2015, the project is in its next phase, extending and refining the main clinical trial findings, identifying factors associated with healthy aging and searching for more ways to improve women’s health.